Density of states, transport, and topology in disordered Majorana nanowires

TL;DR

This paper investigates how disorder affects the topological phases and Majorana zero modes in nanowires, revealing three regimes with distinct transport and topological properties, and connecting theory with recent experimental findings.

Contribution

It identifies three disorder regimes in Majorana nanowires and analyzes their impact on topological superconductivity and Majorana modes, highlighting the complexity of the intermediate regime.

Findings

Weak disorder supports topological superconductivity with end Majorana modes in longer wires.

Strong disorder suppresses topological features, destroying Majorana modes.

Intermediate disorder leads to multiple topological transitions depending on system details.

Abstract

Motivated by a recent breakthrough transport experiment [Phys. Rev. B.107.245423 (2023)] in Majorana nanowires, we theoretically investigate local and nonlocal transport in Majorana nanowires in various disorder regimes, correlating the transport properties with the corresponding local and total density of states as well as various topological diagnostics. We find three distinct disorder regimes, with weak (strong) disorder regimes manifesting (not manifesting) topological superconductivity with clear end Majorana zero modes for longer (but not necessarily for shorter) wires. The intermediate disorder regime is both interesting and challenging because the topology depends on many details in addition to the strength of disorder, such as the precise disorder configuration and the wire length. The intermediate disorder regime often manifests multiple effective transitions between topological and nontopological phases as a function of system parameters (e.g., the Zeeman field), and is consistent with the recent Microsoft experiment reflecting small topological gaps and narrow topological regimes in the parameter space.